The present disclosure is directed to an infrared motion sensor and more particularly to a device which can be installed typically on a wall for observing motion in a given area nearby, and which forms an output for operation when a particular preset level has been triggered. The device is furnished with both manual and automatic modes of operation. The device of the present disclosure is particularly intended to be installed in a wall mounted junction box and, in that sense, is made rather small and is made small so that it is relatively unobtrusive. It is adapted to be mounted at a wall switch location which is typically between four and five feet above the floor, and it has a field of view or vision which encompasses a significant portion of the near vicinity. It is the kind of device which can be used to detect any unintended intruder at all hours of the day or night. While day use is permitted, night time use is the most common time and enables this apparatus to fully exploit its benefits. It is the type of device which can be somewhat tailored to an installation so that, after purchase, it can be mounted and installed on the wall, adjusted once or twice and thereafter be left without subsequent attention. This enables the device to be mounted, adjusted and left after installation and adjustment for an indefinite interval.
Some motion detectors use a light beam and photocell arrangement to detect motion. Another form of motion detector is an ultrasonic standing wave generating system which incorporates a mechanism responding to disturbances in the standing wave. In both instances, some kind of signal source is required, such as a remote lamp. The present apparatus does not require a cooperative remote lamp or the like. Rather it is an infrared detector which is a passive listening device. It is passive in the sense that it avoids the necessity of a companion, but remotely, installed piece which transmits through space to either set up a barrier or field pattern in space for detection of an intruder. This apparatus thus responds to the mere presence of the intruder and provides an output indication when that occurs. The present apparatus is, therefore, a passive device. It is passive in the sense that it does not require a remote cooperative piece of equipment. It is, however, relatively accurate in that it will detect temperature change caused by a target of a certain size within the field of view. It can be adjusted so that images of a person are detected. It can be adjusted to view an area above small pets and game, or any other relatively small animal passing nearby. Whatever the basis for adjustment, such adjustments are made so that a threshold disturbance is required for triggering operation of the device.
The present apparatus is installed with a lens having a wide angle opening or aperture. The field of view can be adjusted by moving the infrared sensitive detector. The present apparatus deploys an infrared detector at a relative location adjacent to a Fresnel lens which directs heat from the immediate vicinity to the detector. The relative position of the detector to the Fresnel lens is changed by means of simple adjustments which move the two components relative to one another; one result of such adjustments changes the field of view somewhat so that this field can be shifted or shaped. The field can be widened or narrowed, and can otherwise be reshaped so that the installation is sensitive to a particular area in view of the device and is able to form a response in a controlled fashion resulting from such movement between the detector and the Fresnel lens. This device is relatively small and does not otherwise significantly protrude into the room and can be routinely mounted within a conventional junction wall box and has a face plate which is approximately equal in size to the face plate of typical electrical fixtures installed on the wall.
The output of the device can be adapted for several type output devices. In one example, it can be a remote alarm sensor so that the signal formed thereby is transferred elsewhere. In another instance, it can be a system which forms a control signal for simply switching on a light at night in the immediate vicinity. There are other ways of using the present apparatus, but one premier feature is that the device makes detection of movement and forms a useful signal which is transmitted elsewhere for switching the output, thereby triggering a change in lighting, sounding an alarm, or providing any other type of output.
One feature of the present apparatus is the relative small size which enables mounting in a fashion most readily accommodated by electrical wiring in and about a building or other area. An important feature related to that is the use of the present device with an adjustable optical system so that the uniformly manufactured device can, nevertheless, be customized at the time of installation. Yet another advantage of the present apparatus is the fact that it has both manual and automatic modes of operation. It can be operated in either mode. When initially placed in the automatic operating mode, there is an override for a few seconds delay in operation to permit a person to set the device and leave the immediate area without tripping the device. In other words, this permits the owner or user to set the device, leave the room while switching a light off manually, and yet leave the apparatus in the automatic mode for detection of an intruder thereafter. Other modes of operation will follow more readily on a description of the manual and automatic modes of operation so that different uses will be understood. It can be used in conjunction with a remote alarm, perhaps to switch on a television camera to obtain an image from the area, sound an alarm, etc., all for the purpose of providing enhanced security for a given area; energy management is available for light fixtures.
The sensitivity of the device can also be adjusted. Sensitivity is in part a function of the direction and field of view of the lens system in conjunction with the detector and its connected circuitry. This can be adjusted to different areas and may change sensitivity. In the circuitry, it can be adjusted so that detected pulse sequences can indicate a more significant intrusion. Suffice it to say, the output of the present device is best connected with some type of device such as a remote light which is switched on at a threshold event of selected sensitivity.
With the foregoing in view, the present apparatus is summarized as a wall mounted relatively simple detector device which provides an output signal on movement in a selected area of an intruder or the like. It is incorporated within a relatively small housing so that it fits within the typical wall opening for a junction box, and it presents a relatively small profile which does not materially intrude into the room. In one form it can be equipped with a slide switch for adjusting the device controlled thereby, typically a lamp or other alarm device. It has additional controls for adjusting the relationship of a Fresnel lens relative to an infrared detector wherein optical sensitivity in the immediate vicinity is adjusted, and it has a threshold sensitivity circuit within permitting a different response to intrusion of a person in the observed area. Many other details will be noted in a review of the specific embodiments set forth below.